Enables MHC class II protein binding activity; cytokine receptor activity; and nitric-oxide synthase binding activity. Contributes to cytokine binding activity. Involved in several processes, including macrophage migration inhibitory factor signaling pathway; positive regulation of macromolecule metabolic process; and regulation of signal transduction. Acts upstream of or within several processes, including antigen processing and presentation of exogenous peptide antigen via MHC class II; regulation of T cell differentiation; and thymic T cell selection. Located in several cellular components, including Golgi apparatus; external side of plasma membrane; and multivesicular body. Part of MHC class II protein complex; NOS2-CD74 complex; and macrophage migration inhibitory factor receptor complex. Is expressed in lower jaw; lower jaw incisor; lower jaw molar; and thymus primordium. Orthologous to human CD74 (CD74 molecule).